Web documents are stored on web servers and are provided to client computers over the Internet upon receipt at the web server of a request for the document in the form of a uniform or universal resource locator (“URL”). The URL specifies the communications protocol by which the information is to be transferred and the Internet address of the host or web server upon which the document is stored. The URL may also specify a directory path and file name for the document. The communications protocol for the web is the hypertext transfer protocol (“HTTP”). Documents or pages stored on web servers and available over the web are generally formatted in a markup language. Markup language web documents contain text and a number of tags which provide instructions as to how the text should be displayed, which text should be hyperlinked to other documents, and where other types of content, including graphics and other images, video and audio segments, application programs or applets, image maps, and icons, that should be retrieved from and displayed in the document. One of the most commonly used standardized markup languages is the Hypertext Markup Language (“HTML”), currently available in several versions. Other standardized markup languages include the Standard Generalized Markup Language (“SGML”) and the Extensible Markup Language (“XML”).
Some document languages such as SGML and XML can represent documents as trees with each node of the tree labeled with a tag and each node's immediate descendants taking in order having tags that satisfy a production corresponding to the parent's tag. Therefore, a document can be represented as a complete parse tree satisfying the production rules of a grammar. XML was created by the World Wide Web Consortium to overcome the shortcomings of HTML. XML allows a document developer to create tags that describes the data and create a rule set referred to as a Document Type Definition (DTD) to apply to the data rules to the data. Several XML parsers have evolved that can read, decode and validate the text based document extracting the data elements in a platform independent way so that applications can access the data objects according to another standard referred to as the Document Object Model (DOM). DOM is an application program interface (API) that defines a standard for developer interaction with XML data structured tree elements. Therefore, XML document and DOM or XML DOM provides developers with programmatic control of XML document content, structure, and formats by employing script, Visual Basic, C++ and other programming languages.
However, the problem with representing an XML document or other markup language document in XML DOM is DOM's inability to represent relationship between elements or represent tangled structures. Additionally, DOM has problems with representing attributes of elements that have been defined in different forms. Accordingly, there is an unmet need in the art for providing a document object model that overcomes the aforementioned deficiencies with DOM.